题干
It is in Nantong _____ you’re going to pay a visit to ______ this kind of radio is made．
A：/; that
B：where; which
C：/; where
D：the; which
答案(点此获取答案解析）
A
+y2=1交于P1，P2两点，线段P1P2的中点为P，设直线m的斜率为k1(k1≠0),直线OP的斜率为k2 ,则k1k2的值为…( )